1. Field of Invention
The present invention relates to a braking and safety control technology of various wheeled motor transportation vehicles, such as automobiles and trains, and also to a wheel braking and safety control technology of taking-off and landing aircrafts.
2. Description of Related Arts
The automobiles are the most typical among the various wheeled motor transportation vehicles, and also one of the major transportation vehicles for humans on the land. The application technologies and products related to the automobile driving braking safety are mainly divided into three types. The first type is the mechanical friction brake, which is further divided according to the structure and the principles into the disc brake and the drum brake. The disc brake is an open structure, which makes use of the friction between the static friction pads and the surface of the friction round disc which rotates circumferentially; the drum brake is a closed structure, which makes use of the friction between the static friction shoes and the cylindrical surface of the braking drum which rotates circumferentially. The friction medium of the disc brake and the drum brake are made of well wear-resistant and heat-resistant metal, semi-metal, few-metal or powder metallurgy composite friction materials. The second type is the automobile tire technology. The performance indicators of the tire technology mainly comprise the adhesive performance, the load bearing capacity, the wear resistance and the driving noise. Preferably, the synthetic rubber, the wide tires and the pattern design are all intended to improve the adhesion of the tires, namely the grip performance, and to ensure the safety and stability of the automobile driving and braking. The wide tires are able to improve the adhesion and load bearing capabilities, but also able to increase the inertia moment and the rolling friction, so as to increase the oil consumption of the automobile. The third type is the conventional automobile electronic safety braking control technology, typically comprising the three standardized application technologies of Anti-lock Braking System (ABS), Electric Brake Force Distribution (EBD) and Electronic Stability Program (ESP). The three standardized application technologies all belong to the electronic safety control method which makes use of the adhesive friction braking force generated between the tires and the road surface by the conventional mechanical friction backward brake, or the adhesive friction traction generated between the tires and the road surface by the motor-driven wheels. The three standardized application technologies all aim for improving the safety and stability in the automobile driving and braking under complicated traffic, which is also the main development direction for the current automobile electronic active safety control technology application and research.
With respect to the structural friction motion, the conventional disc brake has the circumferentially rotating friction which is generated between the friction pads of the brake caliper of the static operation part and the friction round disc surface on the concentric axis of the movable operation part; a disc brake of the present invention has translationally rotating friction which is simultaneously generated between friction pads of a brake caliper of a static operation part and friction round disc surfaces on two eccentric axes of a movable operation part, and between the friction round disc surfaces on the two eccentric axes of the movable operation part and a friction disc ring on a concentric axis. With respect to the energy type, the only energy conversion is from the mechanical friction into the heat energy. With respect to the braking method in the action direction of the braking moment of the brake, the conventional backward braking method only involves the backward braking moment; a dual-directions braking method of the present invention involves co-existing backward braking moment and forward braking moment. No matter for the conventional backward brake or for a dual-directions brake of the present invention, the working performance, the working stability, the wear resistance and the service life of the friction operation parts all depend on an operation pressure among the friction operation parts, a friction coefficient, a friction contact area, a relative motion velocity, a wear rate and an operation temperature.
The disc brake has at least one friction pair formed by the friction pads of the static operation part and the friction round disc surface of the movable operation part which mutually contact and rub with each other. During the operation, each friction pair has the friction disc generate at least one backward braking moment in the direction opposite to the rotation direction of the wheel. The friction of the generated backward braking moment is directly related to the normal force of each friction pair and the friction coefficient, and has nothing to do with the relative friction motion velocity of each friction pair. Given the friction coefficient of each friction pair unchanged, the operation friction of each friction pair is directly proportional to the normal force.
The relative friction motion on the friction round disc surface is the necessary and sufficient feature for the disc brake. The manner of the friction motion on the friction round disc surface determines the structure, the principles, the basic function and the application of the disc brake, and is the basic feature of the disc brake.
The disc brake and the drum brake, widely applied in the various wheeled motor transportation vehicles and the aircrafts, belong to the essential core safety operation part of the primary transportation vehicles in the human social production and life, such as the automobiles, the trains and the aircrafts. Every day, around the world, hundreds of millions of automobiles and tens of thousands of trains are running at high speed; tens of thousands of aircrafts are landing or taking off. The disc brakes or the drum brakes are working at times to ensure the safety in the running of the automobiles and the trains and in the landing and taking-off of the aircrafts, which is a matter concerning human lives.
Among the three primary transportation vehicles of the automobile, the train and the aircraft, the traffic of the road where the tires of the automobile wheels are adhered are the most complicated and volatile. The principles of brake mechanics of the automobile based on the adhesive force between the tires and the road surface determine the close action relationship between the disc brake, or the drum brake, and the wheels and tires of the automobile. Speaking from the angle of tribology, the adhesive force between the tires and the road surface is the friction between the tires and the road surface, which can be expressed by the friction equation (Amontons' Law) of f=N×μ, wherein f is the friction between the tire and the road surface (namely the adhesive force of the tire); N is the normal force between the tire and the road surface; and μ is the friction coefficient between the tire and the road surface (namely the adhesive coefficient of the tire). There are mainly three types of friction coefficients between the tire and the road surface: the coefficient of rolling friction μr, the coefficient of dynamic friction μd, and the coefficient of static friction μs; correspondingly, there are mainly three types of friction: the rolling friction fr, the dynamic friction fd, and the static friction fs. Since μr<μd<μs, given a constant N, then fr<fd<fs.
It seems not so difficult to understand the friction operation principles of the tires adhering onto the road surface which has been reached as a consensus by the worldwide automobile industrial giants. However, different countries have different technical application methods and ways. For example, in the aspects of driving safety, stability and comfort, the U.S. cars are inclined to have heavy chassis to increase the value of N; the German, French, British and Italian cars are inclined to have wide tires and designed tire patterns to increase the value of μs. Regardless of the technical inclinations, the cars of the above countries all have the high-quality synthetic rubber tires to increase the static friction adhesive force between the tires and the road surface, namely the value of fs, so as to ensure the safety and stability of car driving and braking. Japan has always focused on the economy of cars. In order to overcome the “common technical defect” in the above European and U.S. cars, at the outburst of the global oil crisis in the 1970s, Japan timely put forward the oil-saving economical car by reducing the car weight and narrowing the tire, and dominated the world largest U.S. automobile market and the partial European automobile market at once; since then, Japan has successfully become one of the worldwide automobile industrial giants. However, speaking from the angle of safety, the economical techniques of the Japanese car are not completely desirable.
To further explore from the angles of Newton' mechanics, the law of conservation of energy and the tribology, it is not so difficult to understand the tire braking mechanics principles of the conventional backward braking technology. The performance of automobile safety and braking mainly depends on both the braking moment of the backward brake of the automobile, and the friction adhesive force between the tires and the road surface. The larger friction adhesive force between the tires and the road surface, the shorter braking distance and braking time; otherwise, the braking distance and the braking time would be longer. Due to the restriction of the maximal friction adhesive force between the tires and the road surface, when the automobile brakes with the conventional backward brake technology, the automobile is able to brake safely via the maximal adhesive force of the tires only in the critical rolling and sliding friction condition below a certain slip rate percentage between the tires and the road surface. In the emergency braking, if the conventional backward brake owns an overlarge backward braking moment, the wheels would be locked up, which may induce the sliding friction when the slip rate percentage between the tires and the road surface is too large, so that the rubber tires would undergo the surge in temperature, the severe damage and the accelerated aging to shorten the service life and be exposed to the danger of potential flat tire. The sliding friction adhesive force between the tires and the road surface under the overlarge slip rate is smaller than the maximal friction adhesive force therebetween. Therefore, the locked up wheel brake would impair the automobile braking performance and elongate the braking distance and the braking time. Moreover, in the emergency braking, if the left tires and the right tires undergo different friction adhesion with the road surface, the locked up wheel brake would lead to the longitudinal sliding between the left/right tires and the road surface, and greatly lower the lateral friction adhesive force of the tires. As a result, the automobile may run astray or drift, or even turn over at one side, which is quite liable to cause major traffic accidents.
Based on the above knowledge about the principles of tire brake mechanics, in the 1930s, the German BOSCH put forward the well-known automobile safety brake technology, the ABS (Anti-lock Braking System). Actually, the ABS is an electronic safety brake control function which actively controls the maximal braking moment of the backward brake and prevents the wheels from being locked up during braking. In a pulse cycle control manner of “locking-loosening-relocking-reloosening”, the ABS system maintains that the tires are always at a critical friction adhesion state to being locked up during the process of braking on the road surface, and efficiently takes advantage of the maximal friction adhesive force between the tires and the road surface to brake. The EBD (Electric Brake Force Distribution) technology, as a further supplement and perfection of the ABS, effectively prevents the automobile from running astray or drifting due to the uneven brake force distribution between the left tires and the right tires during the emergency braking, and greatly improves the safety and stability in the emergency braking. Along with the progress and development in the key technologies of digital computers and hydraulic pressure regulator, the improvement in the product reliability and the decrease in the production cost, the ABS+EBD braking technology started from Europe in the 1980s and gradually spread across the world. In the middle 1990s, the German BOSCH and BMW officially promoted the advanced ESP (Electronic Stability Program) technology. Even the advanced ESP which focuses on controlling the driving active safety and stability is still under the conventional backward braking technology based on the friction adhesive force between the tires and the road surface.
The train, the automobile and the aircraft, since emerging two hundred years ago, have developed into large-scale industries with the continually progressing design and manufacture, and especially the automobile industry develops at the highest speed. Due to the progress in the manufacture of auto parts and integration, the enlargement in the production and sales, the decrease in the production and manufacture costs, and the increase in the driving safety and stability, the automobile has become one of the most important vehicles in daily life, and the humans have entered the automobile civilization age. In the meantime, the automobile has posed a serious issue of transportation safety in front of the humans. Despite the fact that the various advanced, mature, safe and reliable driving and braking electronic control technologies have been widely applied, the automobile accidents are still happening everywhere and heard all the time, leaving the humans endless disasters and tears. The basic cause still lies in that the braking distance and the braking time of the conventional backward braking technology are too long to satisfy the safe emergency braking during the high-speed driving in the various complicated traffic, which is also the main reason why the current traffic accident rate still maintains high.
The train and the aircraft have relatively low traffic accident rates compared with the automobile. However, the train and the aircraft suffer from the similar braking safety hazard, since using the same conventional backward braking technology and sharing the same principles of brake mechanics and safety braking performance with the automobile.
Both CN 1769130A and CN 2866965Y disclose a dual-direction driving disc brake, which is capable of achieving dual-direction driving under the action of mechanical force. CN 101844192A discloses a high-speed forging mechanical dual-direction clutching brake device, which has lower transmission inertia, and reliable and stable combination and separation of the clutch, and is especially adapted for high-speed press machine. CN 101846148A discloses a disc brake, which is capable of stabilizing the filler blocks at both inner and outer sides, and reducing pulling and vibrating thereof. CN 101852256A discloses a disc braking apparatus, which is capable of stabilizing the performance of the braking filler blocks while braking the disc braking apparatus so as to restrain generating the braking noise, and reducing rolling moment of the barking filler blocks while braking the disc braking apparatus so as to restrain uneven wear and tear of the bearing strips. CN 102128223 A discloses an electronic brake which utilizes the vehicle kinetic energy to brake. Compared with the above Chinese Patents, the present invention has different structure and mechanical principle as follows. When the brake frictionally works, vehicle wheels not only make the friction forwardly to act on the road surface, but also acts on the road surface backwardly, thereby defining the dual-direction braking method of the vehicle wheels. It can be seen that the present invention is a new braking method of the vehicle wheels. An innovation in the conventional safety brake technology of the wheeled motor transportation vehicles is a particularly meaningful project which matters to a series of major social issues, such as the human life and property security. The present invention provides a solution to save the human life, reduce property loss, and lower the automobile traffic accident rate.